My lower yard is glitched..just fall through map

[infernalsock]

I was in upper yard grabbing he fridge recipe.. but when i tried to come back to my base which is on the oak tree I found that all of the terrain is glitched out and is essentially under water. So when i try to go anywhere i basically just fall through the map.. Ive tried reloading backup saves... and repairing the game but nothing is working.